Multiwall bag



Jan. 2, 1934.

T. COTY MULTIWALL BAG Filed May 24, 1933 2 Sheets-Sheet l INVENTOR. THU/VH5 EFIRL DUTY 81%;

ATTORNEY.

T. E. COTY MULTIWALL BAG Jan; 2, 1934.

Filed May 24, 1953 2 Sheets-Sheet 2 INVENTOR. THDMHS EHRL Ear? ATTORNEY.

Patented an. 2, 1934 MULTIWALL BAG Thomas Earl Coty, Watertown, Y. Application May 24, 1933. Serial No. 672,717

7 Claims.

My present invention consists of an improved multiwall bag. The invention is particularly adapted to paper bags, especially to those of large size, the walls of which are composed of a number of webs of very heavy paper, called inthe trade multi-wall bags, which are used for packing cement or other pulverized material.

This application is a continuation in part with an additional figure of drawing and description thereof, designed to show the several independent webs of which the bags are formed, of my prior application Serial Number 408,628, filed November 20, 1929.

The problem of effectively forming the closures of such bags is troublesome, but not so diificult as that of making them remain closed under .the handling they necessarily receive after they are filled. An ordinary size is the quarter-barrel, which when filled with cement for example, weighs 96 pounds. While the side walls are strong enough or easily made so, in making the end closure in the old way the necessary layers of heavy paper become very stifi and diiiicult to work, and even more troublesome and unreliable to seal. In an ordinary valve-bag it is not unusual to employ five webs of a very tough and heavy paper; the forming and folding of the bottom then superposes and pastes one upon another twenty layers of material, making the bottom about as stifi as heavy pasteboard or fiber; there being little or no flexibility; and when the bag is dropped a severe strain comes upon the corners, which crack apart and the bag leaks, wasting the cement or other content and admitting water or vapor to damage the contents.

Bags made under my invention correct this difficulty and the method of manufacture is such that the cost of production is materially reduced, while the daily output per machine is greatly increased. To effect the improvement I provide the bottom of the bag with the desired number 01 layers and the requisite amount of flexibility, so

that at least a large part of the liability of cracking the seal is done away with, as repeated tests have demonstrated. One way of doing that is by cutting away some of the thicknesses of the multiwalls, specifically portions of the intermediate plies at the end or ends of the tube walls which are used to form the closui re, having the inner and outer plies of two of theopposed walls at an end of the bag projecting beyond the cutaway portions, as presently to be more fully described.

Attempts have been made to make the seal of the closure more secure'by interleaving or stepping the layers and sealing them when thus interleaved or stepped. I have found this impracticable, because the formation of bags in that way is too slow and uncertain, and also because the closures are even more rigid than with ordiw nary seals, so that dropping the bag cracks the seals as before. Some other plans including convolu'te wound layers have been proposed, but have not succeeded.

The accompanying drawings show sufiicient 35 details of the process to render it intelligible to those who make bags. Bag machines such as are customarily employed in making valve-bags may be used to form the closures; an example of a desirable type is shown in United States Letters Patent -to Coty and Coty, hereinafter named, but other kinds may be used.

My invention consists in one aspect thereof of the new and improved multi-wall bag formed from a flattened tube having portions of the in= termediate plies or layers of material at an end or the ends 01 the tube cut away between the incisions, leaving the inner and outer plies of the opposed bag walls at the end or ends of the bag at which the closures are formed (one or both) extending beyond the cutaway portions, this being done in the process of forming the bag tubes and the step involved of cutting away the inside layers, as described. The cut-away portions as shown are of less width than the maximum width of the tube walls for a pse presently to appear. Means for,practicing the process is indicated in diagram, forms of machines for making the closures being already in use, for example, as shown in the application 99 referred to below.

Ordinarily this form of bag is made by passing the superposed webs of material through a tuber, which forms or folds the layers of paper along. spaced-apart parallel lines extending lengthwise of the web, pastes the edges together and forms the web into a continuous multiwall tube and then cuts off flattened tube blanks which afterwards are "bottomed, and have the valve-end formed in another machine or me.- chines. A suitable tuber having improved leatures is shown in the Letters Patent to Coty and Coty, Number 1,816,361, dated July 28th, 1931; and a desirable arrangement of bag machines suitably arranged to close one or both ends of the tube blank is shown in the Letters Patent to Coty and Coty, Number 1,792,678, dated February 1'7, 1931.

In the drawings:-

Figure 1 is a perspective v:

oftheemloflll a blank as commonly formed for a multi-wall bag.

Figure 2 is a similar view of my improved construction.

- Figure 3 is a section on the line 33 of Figure 2 of a complete blank according to my invention.

Figure 4 is a similar sketch of a later stage of formation of the old form of bag.

Figure 5 is a perspective sketch, partly broken away, of my improved bag at the same stage.

Figure 6 is an illustrative cross-section of part of one of my improved bags.

Figure 7 is a detail perspective view, partly in section, of one corner of my improved bag, show ing how two of the bottom closure flaps having ends of reduced thickness, are folded over and pasted to one another.

Figure 8 is a diagrammatic sketch of a tuber showing the several webs being formed into a tube.

While the drawings are self-explanatory to one familiar with the usual methods of manufacture, they are thus described.

In Figure 1, A is the old form of bag of as many thicknesses as the nature of the material demands, in the case illustrated five in number. A indicates the part forming the tube side flaps of the closure, separated from the sides by the slits a a.

In Figure 4, the same form of bag is shown in the next stage of the process of manufacture. Here A A are the side flaps; A A the edge folds of the bag before the flaps are turned over. I have not thought it necessary to show the paste, its application being well understood. -It will be seen that duplication and reduplication of the five layers will result in the assembly of many layers of material pasted together, making the construction extremely rigid, as pointed out, and liable to crack open when bending strain comes on the closure.

Figures 2, 3 and 5, showing my improved bag, are to be read together. In these B represents the opposed bag walls of which 12, b are the inner and outer plies or layers, respectively, of the multi-wall, forming the side flaps of the closure; b, b are the intermediate plies or layers from which the edge folds are formed; as seen particularly in Figure 5, when the flaps are folded over and sealed the flexibility of the seal is substantially as great as that of the side-walls of the bag, so that a bending strain or shock is met with sufficient resilience to prevent cracking of the seal. The intermediate plies or layers of the flaps formed between the slits are lettered b b and by referring to the drawings it will be seen that theouter plies b and ,the inner plies b of each wall of the tube at the closure end extend beyond the cut-off portions 22 of the inner plies,

so that the contacting faces of the extended portion of the inner and outer plies band b of each wall may be united to provide two of the cooperating closure flaps and of the edge flaps b. Because of this construction the corners of the bag closure are of full strength, they being formed of all the layers of material, while only the extreme ends of the side flaps b are of less thickness and therefore of greater flexibility to permit them to be more readily and permanently pasted down after folding the-ends of less thickness than the thickness of the main walls of the In Figure 8 I have shown in diagram five independent webs of paper as indicated in Letters Patent No. 1,816,361, and the assembly, separation, pasting and re-assembling of the said webs, in a tuber of the form shown in that patent. In this D to D are the rolls of paper, the webs being marked B to B C, 0, indicate the pasting devices by means of which paste is applied to the inner surfaces of the sheets so that they may be assembled into a single web. C shows the pasting device for forming the longitudinal seam. H is the forming device of the tube. F, F show the rolls of the feed as explained in the Letters Patent referred to, and G is the cut-off for forming the blank.

As I do not claim in this case any of the machines used for forming the tube or closing the bag bottom or the valve end of the bag, no further description of these devices seems to be necessary.

An important part of the new construction is the sealing of the edges of the side flaps with only a part of the thickness of material at the final seal but without reducing the thickness or the strength of the corners of the bag when the flaps have been closed or sealed. Thus I may fold the bottom in the usual way and with the usual number of thicknesses, but with a short portion at the 'end or ends of the intermediate plies or sheets of two of the flaps cut off the web during its formation, leaving'the inner and outer plies of each wall extending beyond the said outoff intermediate plies, so that the bottom is of full strength, but the ends of the side flaps which form the final seal are flexible, substantially as much so as the unfolded walls of the bag as more clearly shown in Fig. 7. It will be apparent that the closure itself may be as rigid as heretofore, but

the folds at the final seal will easily follow the unfolded wall when a bending strain comes on the closure, and thus cracking is prevented. It is this flexibility of the seal, which allows the sheets of the web which are sealed to move together under bending strain, which holds the seal intact.

I have not deemed it necessary to show the later stages of manufacture, since they are those usual in this'art, and may be performed preferably on machines like those hereinbefore referred to, or of other constructions. The new form of bag looks like the old externally, but it is greatly superior in endurance under handling and transportation.

What is claimed is:

1. A' bag-tube blank for use in the manufacture of multi-wall bags, comprising a section out from a flattened tube formed from continuous independent webs of material of substantially the same width the opposite edge portions of which are folded, overlapped and pasted to form the tube, said blank comprising opposed walls each consisting of inner, outer and intermediate plies, each wall having cuts at one end to provide two pairs of opposed closure flaps, each flap of one pair having all the webs of its'wall extending to the free end of the flap and portions of the intermediate plies of the two other flaps being shorter posed walls, each consisting of outer, inner and intermediate plies formed from continuous parallel independent webs of ,material of substantially the same width, the opposite edge portions of which are folded longitudinally and pasted to form the tube, said tube having incisions at an end thereof to provide two opposed pairs of companion flaps which when folded form the bag closure, one pair of said flaps having all the wall plies extending to the ends thereof, a portion of the intermediate plies of the other pair of flaps being cut away between said incisions leaving the outer and inner plies of each of said flaps extending beyond the said cut-away parts and adapted to be united to enclose the same, whereby the free end portions of the said two other flaps will be of less thickness and greater flexibility than the other pair of flaps of full wall thickness for the purpose specified.

3. A multi-wall bag formed from a tube comprising opposed walls each consisting of outer, inner and intermediate plies formed from continuous parallel independent webs of material and having spaced incisions at one end to provide two opposed pairs of co-operating flaps folded relative to one another to form the bag bottom, each of the flaps of one pair being of full wall thickness, and portions of the intermediate plies between the incisions of each wall of the other two flaps at the bottom end of the bag terminating short of the ends of their associated outer and inner plies, the opposed faces of the longer plies of said two flaps being pasted together to provide ends having less thickness and greater flexibility than the other pair of flaps, and the said two pairs of flaps being folded upon each other and pasted together to provide the bag closure.

4. A multi-wall beg formed from a tube comprising opposed walls, each consisting of outer, inner and intermediate plies formed from continuous parallel independent webs of material of substantially the same width, the tube having incisions at an end thereof to provide two opposed pairs of co-operating flaps which when folded and pasted constitute the bag closure, the outer and inner plies of two of said flaps at the end of the tube being longer than and extending beyond the ends of their intermediate plies and having their adjacent faces pasted together to enclose the inner plies and provide sealing end portions of less thickness and greater flexibility than the other two flaps, said latter flaps being of the same thickness as the tube wall, the two pairs of cooperating flaps being folded and pasted together to constitute a bag closure of increased strength and flexibility.

5. A multi-wall bag formed from a section cut from a flattened tube composed of continuous independent webs of material of substantially all the same width folded along spaced longitudinal lines with their edges overlapped and pasted to form the tube, the opposed walls of the tube each consisting of outer, inner and intermediate plies, and said, tube having spaced incisions at one end to provide two opposed pairs of co-operating closure flaps to form the bag bottom, portions of the intermediate plies of two of said flaps being cut away between the incisions and the projecting ends of the inner and outer plies pasted together to provide said two flaps with ends of less thickness and greater flexibility than the other portions of the flaps, said two pairs or two opposed pairs of multi-ply closure flaps folded and pasted to form the bag bottom, the free ends of two of the opposed companion flaps having a less number of plies than the other flaps to provide ends of greater flexibility, the wall portions of greater thickness of said companion flaps overlapping one another, and the free ends of reduced thickness overlying and pasted respectively to the multi-wall portions of greater thickness of the said overlapping flaps, one "inside and the other outside the bag, and the flaps of the other pair having their walls composed of inner, outer and. intermediate plies. '7. A bag formed from a flattened multi-wall tube composed of inner, outer and intermediate plies, the said tube having two opposed pairs of .multi-ply closure flaps at one end thereof folded and pasted to form the bag bottom, two of the opposed flaps which form continuations of the wider side walls of the tube being folded and pasted in overlapping relation and the free end of the outermost of said two flaps composed of the outer and inner plies of the tube well only to provide a thinner and more flexible edge which overlies and is pasted to its companion flap near the base thereof, the major area of all the flaps having the full number of plies of which the tube wall is formed; whereby the bag bottom is strengthened and danger of the outermost flap cracking away is minimized.

THOMAS EARL COTY.. 

